In a wireless network with multiple interfering links, interference alignment (IA) is used. IA is a transmission scheme achieving linear sum capacity scaling with the number of data links, at high SNR. With IA, each transmitter designs the precoder to align the interference on the subspace of allowable interference dimension over the time, frequency or space dimension, where the dimension of interference at each receiver is smaller than the total number of interferers. Therefore, each receiver simply cancels interferers and acquires interference-free desired signal space using zero-forcing (ZF) receive filter.
In practical interference alignment (IA) systems, beamformers (precoding vectors) are computed based on limited feedback of channel state information (CSI). Suppressing residual interference caused by CSI inaccuracy can lead to overwhelming network feedback overhead. An alternative solution for coping with residual interference is to control the transmission power of all transmitters such that the network throughput is maximized. Finding the optimal power control method for multi-antenna IA system requires solving a non-convex optimization problem and has no known closed-form solution.